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        每个程序员都应该有自己的网络类。

        下面是我自己用的socket类，支持所有我自己常用的功能，支持windows和unix/linux。

目录

客户端

服务端

非阻塞

获取socket信息

完整代码

---

客户端

        作为socket客户端，只需要如下几个功能：

//连接到指定的域名/地址和端口
bool Connect(const string & host, unsigned short port);//发送数据
bool Send(const string & str);//发送文本
bool Send(char const * buf, long count);//发送二进制数据//接收数据
bool Recv(char * buf, int buflen, long * pReadCount);//断开连接
bool Close();

        比较复杂的是连接到服务器，因为要处理域名和端口，还要处理主机字节序和网络字节序的转换，但是写好以后就可以简单地用域名/地址和端口调用了。判断传入的参数是域名还是地址可以直接尝试转换成地址，如果失败再进行域名解析。

        Connect代码如下：

		bool Connect(const string & host, unsigned short port)//连接到指定的目标{if (isSTDOUT)return false;struct hostent *ph;T_SA_SIZE len_sa = sizeof(struct sockaddr_in);if (s >= 0){cout << "不能在已打开的socket上操作 " << s << endl;return false;}if (!CreateSocket()){cout << "socket创建失败 " << s << endl;return false;}peersa.sin_family = AF_INET;peersa.sin_port = htons(port);if (-1 == (long)(peersa.sin_addr.s_addr = inet_addr(host.c_str()))){if (NULL == (ph = gethostbyname(host.c_str())))return false;memcpy(&peersa.sin_addr.s_addr, ph->h_addr_list[0], ph->h_length);}if (connect(s, (sockaddr*)(void*)&peersa, sizeof(struct sockaddr_in)) < 0){Close();return false;}getsockname(s, (sockaddr*)(void*)&mysa, &len_sa);getpeername(s, (sockaddr*)(void*)&peersa, &len_sa);int iKeepAlive = 1;setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, (void *)&iKeepAlive, sizeof(iKeepAlive));return true;}

服务端

        作为服务端，关键是这两个功能：

//在指定端口上监听
bool Listen(unsigned short portnum);//接受一个连接请求，返回一个新CmySocket对象
CmySocket Accept();

        Listen其实相当简单，只要先bind到端口即可，当然还可能需要指定使用的IP，不过我的程序没有用到，所以没有写：

bool Bind(unsigned short portnum)//绑定到端口
{if (s < 0 && !CreateSocket())return false;int on = 1;setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char*)&on, sizeof(on));mysa.sin_port = htons(portnum);if (bind(s, (sockaddr*)(void*)&mysa, sizeof(struct sockaddr_in)) < 0){Close();return false;}return true;
}bool Listen(unsigned short portnum)
{return (Bind(portnum)) && (!(listen(s, SOMAXCONN) < 0));
}

非阻塞

        一般用select查询socket是否可读就可以解决阻塞问题（写操作不会阻塞）。但是，有一个坑：

        如果并发执行select，会同时得到可读，从而所有进程或线程进入读操作（通常是服务端的accept操作），但是，只有其中一个能读到，其它进程或线程会被阻塞。这种现象叫做“惊群”。

        对select加锁可以解决问题，但是会降低性能。服务端应该通过别的方式来解决（一般要解决的只是让服务端能遵照指令退出而已）。

        通过select检查socket是否可读的代码如下：

		bool IsSocketReadReady(struct timeval & timeout, bool & ret){fd_set fd;int i;FD_ZERO(&fd);FD_SET(s, &fd);i = select(s + 1, &fd, NULL, NULL, &timeout);if (1 == i){ret = true;return true;}else if (0 == i){ret = false;return true;}else if (-1 == i){ret = false;return false;}return false;}

        还有一个能够快速退出的版本：

		//检查套接字是否可读，seconds为负不设超时，但仍可根据pfNeedBrek跳出bool IsSocketReadReady2(long seconds, bool & ret, bool(*pfNeedBrek)() = NULL){struct timeval timeout;timeout.tv_sec = (0 == seconds ? 0 : 1);timeout.tv_usec = 0;time_t t1 = time(NULL);do{//LOG<<seconds<<" "<<time(NULL) - t1<<ENDI;if (!IsSocketReadReady2(timeout, ret)){return false;}if (NULL != pfNeedBrek && pfNeedBrek()){if (isDebug)cout << "need break：" << s << endl;return false;}if (ret){return true;}} while (seconds < 0 || time(NULL) - t1 < seconds);return true;}

        每次阻塞一秒钟，然后检查是否设置了退出命令。当然我们知道UNIX/Linux的标准的机制是使用信号来中断，不过信号机制可能不同模块冲突，不如靠自己。

获取socket信息

        程序调试经常要知道本地的端口和对方的地址端口，这是通过调用getsockname和getpeername来实现的：

//成员变量public:bool isDebug;//调试输出private:bool isSTDOUT;//输出到标准输出而不是socketint s;//socket -1表示无效unsigned long sendcount;//发送计数unsigned long recvcount;//接收计数struct sockaddr_in mysa;//本地半相关struct sockaddr_in peersa;//远程半相关//服务端接受连接或客户端建立连接后执行：
getsockname(cs.s, (sockaddr*)(void*)&cs.mysa, &len_sa);
getpeername(cs.s, (sockaddr*)(void*)&cs.peersa, &len_sa);//输出内部信息string debuginfo()//输出内部数据结构{string str;char buf[256];str = "";if (isSTDOUT)str += "STDOUT\n";if (-1 != s){sprintf(buf, "%d", s);str += buf;}else str += "未连接";str += "\n";sprintf(buf, "send: %ld\nrecv: %ld\n", sendcount, recvcount);str += buf;if (AF_INET == mysa.sin_family)str += "AF_INET";else{sprintf(buf, "%d", mysa.sin_family);str += buf;}str += "\n";str += inet_ntoa(mysa.sin_addr);str += "\n";sprintf(buf, "%d", ntohs(mysa.sin_port));str += buf;str += "\n";if (AF_INET == peersa.sin_family)str += "AF_INET";else{sprintf(buf, "%d", peersa.sin_family);str += buf;}str += "\n";str += inet_ntoa(peersa.sin_addr);str += "\n";sprintf(buf, "%d", ntohs(peersa.sin_port));str += buf;str += "\n";return str;}

完整代码

#ifndef MYSTD_MYSOCKET_H
#define MYSTD_MYSOCKET_H#ifndef _MS_VC
#include <sys/socket.h>
#include <unistd.h>
#include <netinet/in.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <errno.h>
#else
#include "winsock.h"
#endifnamespace ns_my_std_2
{#define T_SA_SIZE int#ifdef _HPOS
#undef T_SA_SIZE
#define T_SA_SIZE int
#endif#ifdef _IBMOS
#undef T_SA_SIZE
#define T_SA_SIZE unsigned int
#endif#ifdef _LINUXOS
#undef T_SA_SIZE
#define T_SA_SIZE socklen_t
#endifclass CmySocket{public:bool isDebug;//调试输出private:bool isSTDOUT;//输出到标准输出而不是socketint s;//socket -1表示无效unsigned long sendcount;//发送计数unsigned long recvcount;//接收计数struct sockaddr_in mysa;//本地半相关struct sockaddr_in peersa;//远程半相关bool Init()//初始化，s被设置为-1，计数清零，半相关清零{char myname[256];struct hostent *ph;s = -1;isDebug = false;isSTDOUT = false;sendcount = 0;recvcount = 0;memset(&mysa, 0, sizeof(struct sockaddr_in));memset(&peersa, 0, sizeof(struct sockaddr_in));if (0 != gethostname(myname, 256))return false;myname[255] = '\0';if (NULL == (ph = gethostbyname(myname)))return false;mysa.sin_family = ph->h_addrtype;return true;}bool CreateSocket()//初始化并建立一个socket{if (Init() && (s = socket(AF_INET, SOCK_STREAM, 0)) > 0)return true;else return false;}int CloseSocket(int _s){
#ifndef _MS_VCreturn close(_s);
#elsereturn closesocket(_s);
#endif}bool Bind(unsigned short portnum)//绑定到端口{if (s < 0 && !CreateSocket())return false;int on = 1;setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char*)&on, sizeof(on));mysa.sin_port = htons(portnum);if (bind(s, (sockaddr*)(void*)&mysa, sizeof(struct sockaddr_in)) < 0){Close();return false;}return true;}public:CmySocket(int _s = -1)//构造函数，s默认被设置为-1{T_SA_SIZE len_sa = sizeof(struct sockaddr_in);Init();s = _s;if (-1 != s){getsockname(s, (sockaddr*)(void*)&mysa, &len_sa);getpeername(s, (sockaddr*)(void*)&peersa, &len_sa);}}void SetSTDOUT() { isSTDOUT = true; }//设置为标准输出bool Listen(unsigned short portnum)//在指定端口上监听，如果s为-1会先建立socket然后bind{if (isSTDOUT)return false;return (Bind(portnum)) && (!(listen(s, SOMAXCONN) < 0));}bool Accept(int * pNewSocket)//接受一个连接请求{if (isSTDOUT)return false;return -1 != ((*pNewSocket) = accept(s, NULL, NULL));}CmySocket Accept()//接受一个连接请求，返回一个新CmySocket对象{if (isSTDOUT)return false;CmySocket cs;T_SA_SIZE len_sa = sizeof(struct sockaddr_in);cs.Init();cs.s = accept(s, (sockaddr*)(void*)&cs.mysa, &len_sa);if (-1 != cs.s){getsockname(cs.s, (sockaddr*)(void*)&cs.mysa, &len_sa);getpeername(cs.s, (sockaddr*)(void*)&cs.peersa, &len_sa);int iKeepAlive = 1;setsockopt(cs.s, SOL_SOCKET, SO_KEEPALIVE, (void *)&iKeepAlive, sizeof(iKeepAlive));}return cs;}bool Send(const string & str)//发送文本{return Send(str.c_str(), str.size());}bool Send(char const * buf, long count)//发送二进制数据{if (isSTDOUT){std::cout << buf << std::flush;sendcount += count;return true;}long i = 0;while (i < count){int n = send(s, buf + i, count - i, 0);if (isDebug)cout << "socket " << s << " send " << count - i << " return " << n << endl;if (n != count){cout << "socket " << s << " send " << count - i << " return " << n << endl;}if (n < 0){return false;}i += n;sendcount += n;}return true;}bool Recv(char * buf, int buflen, long * pReadCount)//接收数据{if (isSTDOUT)return false;if ((*pReadCount = recv(s, buf, buflen, 0)) < 0){if (isDebug)cout << "socket " << s << " recv  return " << *pReadCount << endl;return false;}if (isDebug)cout << "socket " << s << " recv  return " << *pReadCount << endl;recvcount += (*pReadCount);return true;}bool Close()//close socket 设置s为-1，但其它数据会保持到下一次用这个对象建立新socket时才清除{if (isSTDOUT)return true;if (isDebug)cout << "socket 关闭：" << s << endl;shutdown(s, 2);if (0 == CloseSocket(s)){s = -1;return true;}else return false;}bool Connect(const string & host, unsigned short port)//连接到指定的目标{if (isSTDOUT)return false;struct hostent *ph;T_SA_SIZE len_sa = sizeof(struct sockaddr_in);if (s >= 0){cout << "不能在已打开的socket上操作 " << s << endl;return false;}if (!CreateSocket()){cout << "socket创建失败 " << s << endl;return false;}peersa.sin_family = AF_INET;peersa.sin_port = htons(port);if (-1 == (long)(peersa.sin_addr.s_addr = inet_addr(host.c_str()))){if (NULL == (ph = gethostbyname(host.c_str())))return false;memcpy(&peersa.sin_addr.s_addr, ph->h_addr_list[0], ph->h_length);}if (connect(s, (sockaddr*)(void*)&peersa, sizeof(struct sockaddr_in)) < 0){Close();return false;}getsockname(s, (sockaddr*)(void*)&mysa, &len_sa);getpeername(s, (sockaddr*)(void*)&peersa, &len_sa);int iKeepAlive = 1;setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, (void *)&iKeepAlive, sizeof(iKeepAlive));return true;}bool IsConnected() { if (isSTDOUT)return true; else return -1 != s; }//是否处于连接状态，只对客户socket有意义sockaddr_in const * GetPeersa()const { return &this->peersa; }//检查套接字是否可读bool IsSocketReadReady(long seconds, bool & ret){struct timeval timeout;timeout.tv_sec = seconds;timeout.tv_usec = 0;return IsSocketReadReady(timeout, ret);}bool IsSocketReadReady(struct timeval & timeout, bool & ret){fd_set fd;int i;FD_ZERO(&fd);FD_SET(s, &fd);i = select(s + 1, &fd, NULL, NULL, &timeout);if (1 == i){ret = true;return true;}else if (0 == i){ret = false;return true;}else if (-1 == i){ret = false;return false;}return false;}//检查套接字是否可读，seconds为负不设超时，但仍可根据pfNeedBrek跳出bool IsSocketReadReady2(long seconds, bool & ret, bool(*pfNeedBrek)() = NULL){struct timeval timeout;timeout.tv_sec = (0 == seconds ? 0 : 1);timeout.tv_usec = 0;time_t t1 = time(NULL);do{//LOG<<seconds<<" "<<time(NULL) - t1<<ENDI;if (!IsSocketReadReady2(timeout, ret)){return false;}if (NULL != pfNeedBrek && pfNeedBrek()){if (isDebug)cout << "need break：" << s << endl;return false;}if (ret){return true;}} while (seconds < 0 || time(NULL) - t1 < seconds);return true;}bool IsSocketReadReady2(struct timeval & timeout, bool & ret){ret = false;fd_set fd;int i;FD_ZERO(&fd);FD_SET(s, &fd);//LOG<<"timeout.tv_sec "<<timeout.tv_sec<<ENDI;
#ifdef _HPOSi = select(s + 1, (int *)&fd, NULL, NULL, &timeout);
#elsei = select(s + 1, &fd, NULL, NULL, &timeout);
#endif//LOG<<"timeout.tv_sec "<<timeout.tv_sec<<" select "<<i<<ENDI;if (1 == i){ret = true;return true;}else if (0 == i){ret = false;return true;}else if (-1 == i){if (EINTR == errno){ret = false;return true;//被信号中断不是错误}else{ret = false;return false;}}return false;}//接收数据，可以设置函数来终止bool Recv2(char * buf, int buflen, long * pReadCount, bool(*pfNeedBrek)()){bool isReady = false;if (!IsSocketReadReady2(-1, isReady, pfNeedBrek)){if (isDebug)cout << "IsSocketReadReady2 error：" << s << endl;return false;}if (!isReady){if (isDebug)cout << "not ready：" << s << endl;return false;}return Recv(buf, buflen, pReadCount);}int GetMyPort()const{return ntohs(mysa.sin_port);}string GetPeerInfo()const{string str;if (-1 != s){str += inet_ntoa(peersa.sin_addr);str += ":";char buf[32];sprintf(buf, "%d", ntohs(peersa.sin_port));str += buf;}return str;}string debuginfo()//输出内部数据结构{string str;char buf[256];str = "";if (isSTDOUT)str += "STDOUT\n";if (-1 != s){sprintf(buf, "%d", s);str += buf;}else str += "未连接";str += "\n";sprintf(buf, "send: %ld\nrecv: %ld\n", sendcount, recvcount);str += buf;if (AF_INET == mysa.sin_family)str += "AF_INET";else{sprintf(buf, "%d", mysa.sin_family);str += buf;}str += "\n";str += inet_ntoa(mysa.sin_addr);str += "\n";sprintf(buf, "%d", ntohs(mysa.sin_port));str += buf;str += "\n";if (AF_INET == peersa.sin_family)str += "AF_INET";else{sprintf(buf, "%d", peersa.sin_family);str += buf;}str += "\n";str += inet_ntoa(peersa.sin_addr);str += "\n";sprintf(buf, "%d", ntohs(peersa.sin_port));str += buf;str += "\n";return str;}};
}#endif

(这里是结束)